A variety of stationary and rotating seals, generally referred to as of the labyrinth type, are used in various parts of a gas turbine engine. During manufacture, operation, maintenance, etc, such seals, which include one or more projections or teeth connected with a support structure, can be worn or damaged.
It has become common practice to repair in a relatively cost effective manner certain types of such seal teeth or projections by first removing the damaged portion of the tooth. The same material of the tooth then is reapplied as by welding with a filler wire, with excess added material being removed, such as by machining, to regenerate the tooth. Methods and apparatus for conducting such repair is described in U.S. Pat. No. 4,159,410--Cooper, issued June 26, 1979, and U.S. Pat. No. 4,441,012--Risbeck and Cooper, issued Apr. 3, 1984, the disclosures of which are hereby incorporated herein by reference. As is described in these patents, a filler material in wire form is moved in a reciprocating manner into and out of a weld pool created by a heating source such as an electric arc.
In some cases, because of poor weldability, including poor weld flow characteristics and crack sensitivity of the metal from which the projection or tooth is made, the seal teeth cannot be repaired in a practical manner. Accordingly, when damaged, the costly member may be reshaped for use in another engine position or replaced, rather than repaired.